All publications cited herein are incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. The following description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
In recent years, there has been an interest in the use of infrared (IR) dyes for detection of tagged tissue such as tumors and vessels during surgical removal of tumors in a clinical setting. Infrared dyes are considered superior tagging dyes for marking tissue due to their higher penetration depths, lack of auto-fluorescence in that region of spectrum that can add noise to the imaging, and also lack of absorption from hemoglobin (i.e., blood) and water in that region of the spectrum which can reduce the fluorescence signal. To utilize these dyes in, for example, the clinical operating room environment requires an IR sensitive imaging system, which is capable of acquiring high resolution images in the normal white light visible spectrum, while simultaneously acquiring and overlaying the infrared signal on top of normal visible spectrum images in order to provide a contrast to a surgeon while operating.
However, due to the general absence of applications of fluorescent tumor ligands in surgical oncology, currently there are no imaging systems available commercially that are optimized for near infrared (NIR) fluorescence based resection of tumors. The clinical systems that do exist were primarily designed to detect unbound intravascular indocyanine green (ICG), an FDA approved NIR fluorescent dye. ICG is typically intravenously administered in high doses, and imaging is performed 30-60 minutes after injection. The intravascular fluorescent load achieved with this approach is high, and approved clinical imaging devices have adequate sensitivity for these applications. Examples of such systems include a fluorescent module incorporated into operating microscopes (OPMI Pentero Infrared 800, Carl Zeiss) as well at the SPY® and Pinpoint® systems (Novadaq), and the FluoBeam® 800 (Fluoptics) hand-held unit.
These systems have adequate sensitivity for intravascular imaging, but are not practical for use in, for example, targeted tumor-specific NIR fluorescence. For example, Fluobeam is hand held device with no overlay of white light images but is not designed for practical use as a surgical tool that requires HD quality images in white light, maneuverability, magnification, illumination, and automated co-registration of NIR images. One of the reasons for such low sensitivity is due to less fluorescent photons captured by the imaging system, as such systems may principally use one (NIR only) or two (NIR and visible) cameras with a long pass filter. In a simultaneous visible and NIR capture imaging systems, one camera captures the image in the visible spectrum and second camera captures the fluorescent image. This is achieved by splitting the incident light from the field into two channels using a beam-splitter. One beam transmits the NIR fluorescent light to one of the cameras while the other beam of visible light passes through the beam splitter into the second camera. As the fluorescent excitation and emission of NIR dyes such as ICG have a very narrow stokes shift, the long pass filter causes a significant loss of fluorescent light (FIG. 1), and subsequent detection sensitivity. Fluorescence imaging of tumors requires a targeting moiety to attain high specificity, and enable reliable differentiation between cancer tissue and surrounding normal tissues. To achieve this, doses are kept low and the time between drug administration and imaging is quite long (12-48 hours in most cases) to permit uptake of the probe by the tumor and for the washout of unbound material from normal tissues. This results in markedly less fluorescent signal, making currently marketed systems inadequate for detection. Additionally, these systems can be cumbersome to use in the clinical setting, due to the fact that there are two camera attachments, and require a complete change in the existing setup. This inadequacy of the existing systems drives the need for device innovation to take advantage of the specificity of these novel imaging agents.
Accordingly, there is a need for highly sensitive systems and methods that can record simultaneously visible light image and infrared light image from fluorescent dye. The invention described herein meets the unmet need by providing systems and methods for recording simultaneously visible light image and infrared light image from fluorophores.